CA1090038A - Resole resin binder composition - Google Patents

Abstract

ABSTRACT OF THE INVENTION
The invention relates to a binder composition com-prising a low molecular weight resole resin in combination with boron compounds wherein said boron compounds are present in from about 1 to 30 parts per 100 parts by re-sole resin solids, said composition having a pH of about 2-6 and said resole having a viscosity of from about 5 to 5000 cps. said binder provides laminates having superior electrical and flame retardant properties.

Description

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¢ , ' ¢ C-06-12~0~16 ~90~38 ; A RESOLE RESIN BI~IDER CO~POSITION

BACKGROUND OF THE INVENTION
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In order to get acceptable processing speed from resole resin impregnated substrates, it is common practice to use phenol-formaldehyde resoles which have high molecular weight, that is, they are reacted to near the gel point in the prepara-tion. These materials have to be dissolved in an organic sol-, f ~ vent to provide viscosities low enough to be processable. The high viscosity leads to poor resin penetration into many sub-strates, with the result being certain poorer properties of the finished article such as water absorption and appearance. Also, during resin preparation the resin high viscosity leads to poor : . ., : ~ heat transfer~ longer resin cycles, and molecular weight distri-. ~
- bution becomes too broad.

i 15 Thus, in accordance with the present invention, resole .. . .. .
resin binder compositions are provided with greatly accelerated cure rates that provide laminates having excellent electrical and fire-retardant properties. It has been discovered that the :; addition of 1 to 30 parts of boron compounds per hundred parts of resole resin solids provides novel binder compositions wlth . :...
great utility. Because of the boron additive~ resole resins can be made of low molecular weight and narrow molecular weight dis--:-.,.-; ::
~ tribution giving a more reliable, reproducable resin product in . ........................... .
shorter cycles. No organic solvent need be used, eliminating a .. . .
-`- 25 large pollution contributor. Penetration of this low molecular 7 ., ~ ~', ~; weight resin into any substrate is excellent. Processing speed s . ..:., ~
is equal or better compared to currently used resole varnishef"
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2 ~ and final laminated product properties are better, especially . electrical and flam resis-tance properties.
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~` -' C-06-12-01~16 i~o~ ()3s ~:'.,` ` ' ~; SUMMARY 0~l TH~ INV~NTION
,-' This invention relates to a binder composition compris-ing a low molecular weight resole resin and a boron compound .' curing accelerator, selected from the group consisting of boric acid, dlammonium tetraborate, diammonium octaborate, diammonium ;':' . .
` pentaborate and mixtures thereof, said boron compound being ,~'`` '~ .
- present in from about 1 to 30 parts by weight per 100 parts of ~: resole resin solids, said composition having a pH of about 2-6 and said resole resin having a viscosity of 5 to 5000 cps.
DETAILED DESCRIPTION OF THE INVENTION
Resole Resins `: The phenol-formaldehyde resole resins of the present in-, ' ! ~
; vention are prepared from a phenol selected from the group con-x: ~:
` sisting of phenol, substituted phenols and substituted phenol -. .~ .
mixtures and mixtures thereof.
The substitvted phenols useful in the resins of this in-: vention are all phenols that have a-t least one reactive position open in the ortho or para position. Phenol and such substituted .. `` phenols or their mixtures can be used. Substitu-ted phenols in-clude all phenols having at least one attached radical selected from the group consisting of alkyl, aryl, cycloalkyl, alkenyl, ~-:y. .~.
- cycloalkenyl~ alkaryl, aralkyl, carbocyclic, halogen and mix--~ .: ., - tures thereof.

Examples of substituted phenols include: phenols sub-stituted ~rith straight and branched chain alkyl radicals having 1 to 16 carbon atoms, e.g., cresol, isopropylphenol, 2,3-xylenol, , ....
:^ 3,5-xylenol~ 3,4-xylenol, 2,6-xylenol, mono and disubstitute~

~ butyl, amyl, octyl, nonyl, decyl and dodecyl phenols, aryl sub~

'r'-,,l stituted phenols, e.g., phenyl phenol and naphthyl phenol;
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..... .
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C-06-12-OIil6 cyeloalkyl phenols, e.g., terphenylphenols, e.g., using limonene, ~ , . pinene, methadiene, cyclohexyl and cyclopentyl; cycloalkenyl phenols, e.g., cyclopentenyl, dicyclopentadieneyl and metha-cyclopentadieneyl phenols; alkenyl phenols, eOg., allylphenol, styrene, butenylphenol, pen-tenyl phenol, hexenylphenol; alkaryl ` ~ phenols, e.g., tolylphenol, xylylphenol, propylphenylphenol, , ... .
:.'.. ; aralkyl phenols, e.g., benzyl, phenethyl, alphamethyl, pheny-` ethyl, indyl and cymyl phenols bisphenol A, bisphenol F, halo-phenols, e.g., chlorophenols, bromophenols, 2,ll dichlorophenol, , 10 2,6,dichlorophenol, etc.
'" ! ' ~
~ The substituted phenol mixture used to make such resin . . -~; - i.s prepared by reacting phenol under Friedel-Crafts conditions ~ with a controlled mixture of carbocyclic compounds. The mixture :` ,,"
of earbocyclic compounds comprises (on a 100 weight percent .`~ 15 basis when in a form substantially free of other materials);
(A) From about 10 through 40 weight percent of compounds each moleeu]e of which has:
~i ~ (1) the indene nucleus, . .,-, .
~ (2) from 9 through 13 earbon atoms, i~
~ 20 (3) as nuclear substituents from4.,~.~.
~ 0 through 4 methyl groups, ., ,,:.
(B) From about 5 through 70 weight percent of `-; eompounds each moleeule of which has:
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(1) the dicyclopentadiene nucleus, (2) from about 10 through 13 carbon .., ;-l atoms, ~i (3) as nuclear substituents from 0 : through 3 methyl groups, . .. . . .
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C-06-12-01~16 (C) From about 15 through 65 weight percent ; of compounds each molecule of which has:
1) a phenyl group substituted by a ~,: vinylidene group, ?~ ..... 5 (2) from about 8 through 13 carbon !: ~ `
~ atoms, ,,.-~ . .
~;j (3) as substituents from 0 through

3 groups selected from the class consisting of methyl and ethyl, (D) From about 0 through 5 weight percent divinyl benzene, (E) Provided that the sum total of all such ~:; ` compounds in any given such mixture of carbocyclic compounds is always 100 ..,,.:.. :
weight percent. ~ ~

Such substituted phenol mixtures and the resole resins ~-..... . .
,~ prepared therefrom can be prepared by methods disclosed in U. S. P. 3,761,448.

Resole resins are easily made by reacting phenol and 2~ formaldehyde in the presence of basic catalysts. Examples of low molecular weight phenol-aldehyde resole resins having ", ~ characteristics suitable for use in this invention are as ~,', ` follows:

~`~ i."`'i Phenol (100 parts) 50 percent formalin (111 parts), and triethylamine (5:parts) are charged to a vessel. ~he resulting mixture is reacted at about 70C. until the free formaldehyde-content is less than about 4 percent, after which the mixture is cooled. ~he product is a low molecular weight water soluble ,~ , ....... .
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1~90038 C-06-12-0ll16 phenol-formaldehyde resole resin having ôl percent soli~s, 9 ;; percent H20 and a viscosity of 2400 cps.
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Phenol (100 parts), 50 percent formalin (80 parts, and triethylamine (2 parts) are charged to a vessel. The resulting mixture is reacted at about 85C. until the free formaldehyde '''``'~"`
content is less than about 2 percent, after which the mixture is ~r ~ cooled. The product is a low molecular weight water soluble :
i~ phenol-formaldehyde resole resin having 78 percent solids, 8 : ''-', .
~ 10 percent H20 and a viscosity of 1100 cps.
,,- , .
; EXAMPLE 3 Phenol (100 parts), 50 percent formalin (70 parts) and ~`` triethylamine (2 parts) are charged to a vessel. The resulting mixture is reacted at about 85C. until the free formaldehyde content is less than about 1 percent, after which the mixture is ~,, ~
~^ cooled. The product is a low molecular weight water soluble . , .:
~ phenol-formaldehyde resole resin having 74 percent solids, 4 .
:: .: ..
~` ~ percent H20 and a viscosity of 650 cps.
.:: :.
EXAMPI.E 4 ','-'''~
Phenol (100 parts), 50 percent formalin (111 parts) and calcium hydroxide (2.0 parts) are refluxed at 70C. to a free formaldehyde level of leSS than 4 percent. The resin is cooled and carbon dioxide bubbled into the resin to a pH of 7Ø The ~, . . .
salt formed is filtered from the resin. The product is a clear, ,. . , ' ~.; 25 low molecular weight, water-soluble phenol-formaldehyde resole ., " ~, .
r~ resin having 83 percent solids, 7 percent H20 and a viscosity of , ............................................................... .
` ~r 3300 cps, , . . .

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~- EXAMPLE 5 .t. ~ .
Phenol (100 parts) 5 50 percent formalin (111 parts) and 50 percent aqueous sodium hydroxide (4 parts) are refluxed at ; 70C. to a free formaldehyde level of less than ~ percent. The resin is cooled and phosphoric acid added to a pH of 7Ø The ~` salt formed is filtered from the resin. The product is a clear, , . .~., ~-~ low molecular weight, water-soluble phenol-formaldehyde resole i~ having a solids of 80 percent, 7 percent ~I20 and a viscosity of .;-.: .
'~', 3000 cps.

;c 10 EXAMPLE 6 , - :, ~ Cresol (40 parts), phenol (60 parts), 50 percent forma-- lin (111 parts) and triethylamine (5 parts) are refluxed at ` 70C. to a free formaldehyde content of less than 4 percent, and . .............. .
~n' the mix-ture cooled~ The resin is a low molecular weight phenol-.;:...,:
~i 15 formaldehyde resole product having a solids of 80 percent, 9 per-cent ~120 and a viscosity of 2000 cps.
, ,,. ~ . .
j, l Alkylated phenols of many -types can be used to make low , ,~-,, .

~ molecular weight resole resins. These substituted phenols are , ~ ............ .
~ prepared by reacting phenol under Frledel-Crafts conditions with , ""~
an unsaturated compound or mixtures of such compounds.
~, To react phenol with such a compound mixture~ it is con-venient to use Friedel-Crafts conditions, as indicated.
The term "Friedel-Crafts conditions~' as used herein re~ers to the conventional conditions known to those of ordinary . . .j .
, 25 skill in the art used for the alkylating or arylating of hydro- ;!
carbons (including phenol) by the catalytic action of aluminum ,~` chloride or equivalent acid catalyst in the presence of appro-priate heat and pressure. In the practice of this invention, the phenol and suitable Friedel-Crafts acid catalyst are mixedS
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- brought to the proper te]rlperature, and the compound mixture ~etered into -the acidified (or catalyzed) phenol.
For purposes of this invention, the reaction of the com-.: ~ .
pound mixture with phenol is preferably carried out at tempera-tures in the range of from about 25 to 200C. although higher and . - .:
lower temperatures can be used. Also, the reaction iæ preferably ~!``'` ~ conducted under liquid phase conditions at or below atmospheric ! ., pressure although superatmospheric pressures can be used.
-; Friedel~Crafts catalysts which may be used in place of aluminum chloride, or together with aluminum chloride, include:
- (A) Other inorganic halides, such as gallium, titanium, antimony and zinc halides (including ZnC12), (B) Inorganic acids such as sulphuric, phosphoric and the hydrogen halides (including HF);
` 15 (C) ~ctivated clays, æilica gel and alumina;
; (D) BF3 and BF3 organic complexes, such as complexes of ~`~ BF3 with organic compounds, such as ethanol, butanol, glycol, ::.:
~- phenol, cresol, anisole, ethyl ether, isopropyl ether, di-n-t. butyl ether, formic acid, acetic acid, propionic acid and the Iike, or with inorganic acids, such as phosphoric acid, sulfuric acid, and the like, and . ."..,.j ~- (E) Alkyl, aryl and aralkyl sulfonic acids, such as ethane-i~ sulfonic acid, benzene sulfonic acid, benzene disulfonic acid, ~ chlorobenzene sulfonic acid, 3,1~-dichlorobenzene sulfonic acid, -:,"' ~-, 25 cresol sulfonic acids, phenol sulfonic acids, toluene sulfonic acids, xylene sulfonic acids, octylphenol sulfonic acid, -naphthalene sulfonic acid, l-naphthol-4-sulfonic acid, and th~
like.
, ~ When BF3, aæ such, is employed, it is conveniently fed "~ ' '` :

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~ 90038 .. , . ~ c-o6-l2-o4lG
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to a reac-tion mixture in gaseous f`orm.
While any combination of compound starting miY~ture, phenol, and catalyst can be used, it is particularly convenient ::; to react phenol with the compound mixture in the presence of less than about 10 weight percent (based on the starting phenol) - of acid catalyst. Typically, from about 0.1 to 1 weight percent o~ Friedel-Crafts acid catalyst is employed (based on phenol).
~:, - The reaction mass is heated to a temperature in the range of from about 25 to 200C. The rate of this reaction is ...,~
dependent, to some degree, on the temperature employed. In gen-` eral, the reaction is rapid, and a complete reaction between ' ,'''1 , pheno] and compound mixture is preferred. Generally, a total ~-~ heating time of from about 10 minutes to 4 hours is employed.
- The various process ~ariables are summarized in Table I below.
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TABLE I
Process Broad Preferred ~ariable range range ~'~
Temperature About 25 About 40 to (C.) to 200C. 125C.
Reaction About 4 About 10 to Time hours 30 min.
~;
,S`,,'~'` Catalyst Less than About 0.1 to `.' (based on about 10 1.0 weight ',`,''''.'t,,l phenol) weight percent -~ 25 percent ~:.,:;
The properties of a gi~en so-substituted phenol product are affected by the process conditions used to make that product ~'.."

~ (e.g. molecular weight distribution, color, and the like). The ,~ ., .:
- resulting reaction product is, as those skilled in the art wi~l ~ 30 appreciate, a complex mixture of ~JarioUS different substituted ~....~, ~ phenols produced from the reaction of phenol under Friedel-Crafts : . ~
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~090038 ,,. C-06-12-0l116 conditions with the compound starting mixture to produce phenol c; molecules which are substituted on ring carbon atoms.
In general~ to produce a resole for use in this inven--tion, a phenol, as just described, is neutralized under aqueous ',~!; 5 liquid phase conditions as by the addition of base and then from ~ ~ about 1.0 to 3.0 mols of formaldehyde per one mol of phenol is.;~ mixed with the phenol (now itself a starting material). Water may be added with the formaldehyde. Formalin is preferred as a source for formaldehyde. Also, a basic catalyst material, such . 10 as ammonium hydroxide and/or amine se]ected from the group con-sisting of primary amines (such as ethylamine, isobutylamine, : ethanol amine, cyclohexylamine, and the like), secondary amines tsuch as diethanol amine, piperidine, morpholine, and the like);
.; , ~ and tertiary amines (such as triethylamine, triethanolamine, di-`.j 15 e-thyl cyclohexyl amine, triisobutyl amine; and the like) is in-` , troduced into the reaction mixture include metal oxides and hy-., ~, .
droxides. Preferred amine catalysts have molecular weights below ~' about 300 and more preferably below about 200. The amine cata-- lyst may include hydroxyl groups which tend to promo-te solubil--~ 20 ity of the amine in the reaction mixture. This basic catalyst ~ itself thus can be used to neutraJ.i~e the starting substituted ;~
phenol. The pH of this reaction mixture is maintained from (7.0 .~ .
and preferably above about 7.5) but below about 8.5. This re-action mixture is then heated to temperatures of from about 60 25 to 100C. for a time sufficient to substantially react most of the formaldehyde and thereby produce a desired resole product.
Times of from about 20 to 180 minutes are typical. Aqueous liquid phase preparation conditions are used.
It will be appreciated that the formaldehyde to phenol .~,' ' -~.

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~; mol ratios herein described have reference to the -total amount of phenol present before a reaction, including the phenol which -~`` is substituted by the compound mixture as described above.
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To optimize electrical properties in resoles used in ~ 5 this invention, it is preferred to use as a basic catalyst, when : ``, `` reacting such substituted phenols with formaldehyde to make re--,;~ sole resins, one which is non-ionic and non-metallic in charac-~: ' ~ ter, -. `` '-The resole product produced by reacting the phenol with formaldehyde as described above is one composed of methylolated substituted phenol which has been methylolated by the formalde-hyde to a desired methylol content. As those skilled in the art fully appreciate? the methylol content and the degree of advance-~- ` ment are readily controllable, so that one can optimize such a ~ 15 resole resin for use in a particular application, For purposes ,~ of this invention, a phenol-formaldehyde resole resin or resole ~,~ can be regarded as being the reaction product of the above-de-scribed phenols and formaldehyde under the aqueous base catalyzed conditions as described herein which product can be thermoset by ~i heat alone without the use of a curing catalyst.
The following example shows how the low molecular weigh-t, ,:, substituted phenol resole resin is prepared.
.:;

Charge lO0 parts phenol and 0.3 part concentrated sul-f ,. ~
furic acid to a reaction vessel and adJust the temperature to 75C. Meter in 20 parts styrene over lO minutes. The reaction temperature will rise to 100C. due to the exothermic reaction o~ styrene with phenol. Hold the`reaction mixture at 100C, for lO minutes, cool to 50C, and add 5 parts triethylamine, 80 parts .~ . .
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formalin and react at 70C. to a :~ree formaldehyde level of less than 2 percent. Dehydrate the resin to a refractive index of . -:
1.559. The product is a clear, low molecular weight, water ~` soluble resole resin made with phenol and styrene substituted ',:
phenol.
- ~ The following examples are presented in tabular form.
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-~ The process in all instances is shown in Example 7 except that ... .
; the indicated variables are altered as shown in Table II below.
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~ TABLE II
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-~ 10 Unsaturated '`.. ~. Gompound MixtuY e ( 1 ) '. Example _~ype Amount Tem~. C.
.... ; .
,' ` ! . o 1 30 100 ~j: 9 2 `-' 15 10 3 '- 12 5 ~

. 14 7 100 ~`' 20 15 8 16 ~ ~ :
17 10 ~ ~ 125 . - . .
~ (1) Numbers listed under ~Type Unsaturated - Compound Mixture" each designate a ~ 25 specifiç composition as shown below.
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~-:` . 1 2 3 4 5 6 7 8 ~ 10 styrene 25 5 50 50 50 50 ` ~-methyl ~ styrene 25 100 5 50 : :~ 30 vinyl toluene 25 100 30 50 :
; indene 25 100 30 50 dicyclo-penta-` 35 diene 30 100 50 .
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All these resoles are characteristically one-phase, clear liquid solutions, each having a viscosity ranging from :, .
, ~ .
:~ about 5 to 5000 centipoises. The eY.act viscoslty of` a gi-ven -~ solution depends upon many chemical process and product vari-i~'`'.''~ , ables. For impregnating applications, viscosities of from about 50 to 2000 centipoises are preferred. Dilution with water or . "~.,~ . .
organic solvents is used to adjust the viscosity into preferred ranges.
- ~ The total solids content of a given resole resin can be ~ .. ~,..
as high as about 85 weight percent or even higher, and as low as about 20 weight percent or even lower, but preferred solids `- contents usually fall in the range of from about 25 to 75 weight , .:
percent.

~- When used for impregnation and reinforcing purposes, the resole resins of this invention are useful for impregnating .. ..
i cellulosic paper, asbestos paper, and other non-woven sheet .. ~ :. ..................................... .
~ ~ structures as ~ell as woven fabrics (cotton, glass f`ibers, nylon, ~ .- . .......................................... .
etc.), etc. Impregnation can be accomplished by any convenient . means, including dipping, coating, spraying, mixing or the like.
The so-impregnated material is dried to lower the volatiles con-~` tent and then heated to advance the resin to the proper degree for the intended use. The resoles of -this invention are usef`ul in the preparation of laminates, such as those made ~rom such impregnated sheet materials. Such laminates are used in elec-trical applications as supports or as insulation for conductive elements. The laminates are generally manufactured in a sheet or ~` block f`orm which is then punched or otherwise machined to provide desired configuration for a particular end use.
; The resole resins of this invention are also usef`ul in ,~, ............................................. .

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~ 00339 ~ C 06-12-0416 : `
the manufacture of cloth laminates, and automotive oil filters.
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A suitable oil filter media, for example, is prepared by im-pregnating ~ith a resole of this invention, cellulosic fiber ` paper modified with a synthetic iiber (polyester, or the like) d;-- 5 and having a thickness of from about 5 to 20 mils. Sufficient ~ r", .
of the resole resin of this invention is used to obtain an im~
.:" '. .
pregnated sheet member having a cured resin content of about 35 to 65 percent preferably about 15 to 25 percent, based on the weight of the paper. After such paper is so impregnated, it is ., -;
heated to advance the resin to a so-called B-stage, and then is ~; corrugated or pleated to form the filter element. The filter element is then assembled with the end use filter container and ,:
heated to 250F. to 350F. for from 5 to 20 minutes to cure the - ' resin. When cured, the product has good flexibility and low :: . :
tendency to crack during use.

Bo_on Compound Accelerators i:
The accelerators employed in the composition of the -:
present invention are boron compounds selected from -the group consisting of boric acid H3B03, diammonium te-traborate ;

;-~ 20 (NH~)2o2B2o3-4H2o, diammonium octaborate (NHI~)2o4B2o3-6H2o~

~ diammonium pentaborate (NIII~)2 o5B2o3-8H2o and mixtures thereof.

~ . ., . ~ ~
`~ Such preferred boron compounds are described in the Encyclopedia .
of Chemical Technology, 2nd Edition, 1964, Interscience Pub---' lishers, New York, N. Y., Vol. 3, pages 609-648.

Boron compounds as described above are added to the i ..:.
i resins described in the examples to give the desired properties of lower dry rubber for fast treating yet retain 10W molecular ,. . .
weight for good impregnation into a variety of substrates, en-hanced electrical properties, no organic solvent needed for .;, .: :..
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~: C-06-12-01116 : lower pollution potential and better flame resistance.
The amount of boron compound can vary f'rom about 1 part per 100 resin solids to about 30 parts (same basis). Prefer-. , ably, between 2 and 10 parts are needed to obtain the desired ~-~. 5 end results listed aboveO Excessive amounts of` boron compounds . :
are not soluble or if soluble, crystalli~e out when cold. When ~, boric acid or the ammonium borates are used alone, the pH of resoles is usually about 2-6. This may lead to corrosion and the above mentioned insolubility in certain resoles. This prob-~; 10 lem is solved by raising the resin mixture pH with ammonium hy-droxide to about 7-10. Dry rubber lowering effectiveness is re-, ' duced only slightly, and corrosion to metals such as iron is avoided and compatibility is improved.
. The boron compounds are dissolved in the resole resins by conventional mixing as can be appreciated by those skilled in the art. The solutions formed are stable at temperatures usually used ~or storing and shipping resole resins binder com-` positions.
Binder Compositions The binder composition has, in combination, a resole resin comprising resin solids of from 20 to 85 percent, prefer-i ,~,, ~
,ii' ably 25 to 75 percent, by weight, a dissolved water content of' "'.''; .
0.5 to 35 percent, preferably 2~0 to 15 percent by weight based on said resole resins solids, said resole having a viscosi-ty of ',!:,','~ 25 from about 5 to 5000 cps pref'erably 50 to 700 cps, said composi-'~f'.'`'` tion having present f'rom about 1.0 to 30 parts, pref'erably 2 to 10 parts of a boron compound based on said resole resin solidb.
The binder composition can be a solution wherein said ~ '' , resole resin and accelerator are contained in a solution com-i. .....
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~i 3L0~0(~38 .~ C~06-12-0l~16 prising about 20 to 98 percent, preferably 25 to 75 percent by weight of resin solids, about 2 to 80 percent, preferably 25 to ~. 75 percent by weigh-t water and about 0.5 to 5 parts preferably `c 1 to 3 parts of a boron compound based on said resin solids.
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The binder composition can be a solution or varnish '. ~ .
.- ~; whereln said resole resin and accelerator are contained in a solution comprising:
~s~
~ (A) about 20 to 85 percent by weight of resole . ~. . ..
~ : resin solids, r - 10 (~) about 0.5 to 15 percent by weight of water, :
, .
~ ~ (C) about 0.5 to 5 parts by weight accelerator ,:.
s~`. per 100 parts of resole resin solids, and ~-~ (D) the balance up to 100 percent by weight of . said solution being an organic liquid which ç;, ~: ~ 15 (1) is substantially inert to said . . resin and water, . (2) evaporates below about 150C., at ~ atmospheric pressures, ,,,,,~. ,:
~ ~ (3) is a mutual solvent for said resin, ,.;:. -.~
~`......... 20 said water and said accelerator, being present in an amount sufficient .~ to maintain a solution.
The organic liquid is a relatively volatile, inert or-~; ganic solvent medium having the properties described above.
.; . ..:
~" 25 While the organic li.quid used has properties as indicated above, it wil]. be appreciated that such liquid can comprise mixtures of ~:~; different organic liquids. Preferred liquids are lower alkanols (such as ethanol and methanol) and lower alkanones (such as ace-.. tone or methyl ethyl ketone). The term "lower~' refers to less ~,.`...
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1~9~)038 . c-06-12-041G
~ than 7 carbon atoms per molecule as used herein. Aromatic and -~ aliphatic (including cycloaliphatic) hydrocarbons can also be . . . ~ .
employed as solvents for a given resin, including benzene, toluene, xylene, naphthalene, nonane, octane, petroleum frac-tions, etc. Preferably, the total water content of a solution .
of the invention is below about 15 weight percent, and morepreferably falls in the range of from about 0.5 to 5 weight percent.
Those skilled in the art will appreciate that care ~; 10 should preferably be taken to use an organic liquid system in which the phenolic resole resins are completely soluble as well ~-- as any water present. Adding, for example, a ketone or an ;: .
ether-ester solvent like butyl Cellosolve will generally improve the water tolerance (ability to dissolve water) of a solvent system.
r,.~
EMBODIMENTS

; The following examples are set forth to illustrate more clearly the principles and practices of the invention to one . skilled in the art. They are not intended to be restrictive ,:.. .-:
but merely to be illustrative of the invention. Unless other-wise stated herein, all parts and percentages are by weight.
~: Dry rubbers of other phenolic resin resole mixtures with ~.~..................................................................... . ..
;j~ acids and ammonium salts of acids were run to determine how , .......
broadly the dry rubber lowering effect was. Please see attached Table III. Dry rubber correlates with process speed. Oxalic : .".~:
acid, benzoic acid, acetic acid and lactic acid give increased dry rubbers at 3.3-5.1 pH, whereas sulfamic acid gave much lower . .. ~ .
dry rubber at 7.5 pH (compared to the control at pH 8.2). Sul-furic acid and phosphoric acid gave reduced dry rubbers at low .'~
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~ C-06-12~0416 -' pH. Thus, there is no correlation of pH and dry rubber. Of' all the ammonium salts tested, ammonium borate gave the most dry :- rubber lowering and also was the only salt to give low pH (~.0).
~, ' i All other salts gave ~5.7 pH. Since boric acid is very wea~, - 5 the low pH is attributed to the presence of' polyhydroxy com-pounds f'orming a stronger acid with one monoborate ion B(OH)4 and two molecules of` polyhydroxy compound. When running dry ....
- rubbers on resin mixtures it was noted that NHIl borates and ,- ~ boric acid were the only additives to give a rapid molecular . :..
'~ 10 weight build-up on the cure plate. All other additives shown on ; the Table were of low viscosity for most of the test and then ,: .. . .
~. rapidly gelled.
. ~ .
It is evident tha-t none of the substances tested in Table III (except borates) will give the combination of` fast processing; better electricals and f'lame resistance.
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. ` 5 Examples 40 to 46 and ~able IV are shown below illus i~ trating the e~fects of boric acid on several resole resins.

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C~ 0 6 -12 -O 11 16 5,~`.;,~ Footnotes:
;' ':., .~; (1) 135C. air oven, time to acceptable flow ~.. .
;~ 1 laminate resin contents ~ 54-57%
;` paper used - cotton linter , 5 cure conditions- 30 minutes/150C./1000 p5i t~
~m` (2) 24 hours in 23C., water = D24/23 ~: .
.,`' (3) ( ) = highest number, test number is average of six 10~5 ignitions

(4) CondO A = as is i':~ `:;
~`,* 10 (5) Loss Index ~ product of dielectric constant and dissipation factor r ~" (6) alkylated phenolic resole high molecular ~` ~ weight resin - viscosity of 25,000 cps with ~ about 7 percent H2 ,~ '' 15 (7) RESIN EXAMPLE B
-:~ (8) RESIN EXAMPLE L
..:
It is evident ~rom Example 43 that advanced resole resins provide laminates with poorer electrical properties as :-i~ - compared to the low viscosity resoles of the present invention ` 20 used in combination with said boron compounds, as accelerators.
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The resin OI Example 3 (100 parts) was used in combina-~': .
tion wlth boric acid to prepare binder compositions. The pH of ` binder composition was adJusted with ammonium hydroxide to test ,. .
r";'`"" 25;i; curing rates and iron corrosion. Table V below shows the re-sults of these tests.

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~ Boric 150C. Iron ,.. ~-.i Example Acid ~HIlOH pH DR Corrosion .. , 47 0 7.9 540 none ., 5 48 8 0 2.6 130 yes 49 8 yes 5.7 130 yes , .
~; 50 8 yes 6.9 105 slight ~, 51 8 yes 8.2 105 none .. It is evident that curing rate o~ the composition is ~` 10 retained at high levels with boric acid accelerators in the presence of NH40H with corrosion being controlled at higher pH
~- values of greater than 7.
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~:~ EXAMP~ES_52 - 53 ~.. ..
~ ` Examples 47-51 were repeated using 8 parts o~ ammonium ~:
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~ 15 tetraborate and ammonium pentaborate respectively. The pH o~
`t ~ '' ' the compositions were ~ound to be about 3. The compositions .:`, were adJusted to a pH of about 8 and the dry rubber rates were , :., : .
~,.' found to be about 120 seconds with a control o~ about 450 seconds . - showing that NH40H can be used to adjust pH into the range of' ~ 20 7-10 without affecting cure rate.

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Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A binder composition comprising a low molecular weight resole resin and a boron compound curing accelerator, selected from the group consisting of boric acid, diammonium tetraborate, diammonium octaborate, diammonium pentaborate and mixtures thereof, said boron compound being present in from about 1 to 30 parts by weight per 100 parts of resole resin solids, said composition having a pH of about 2-6 and said re-sole resin having a viscosity of 5 to 5000 cps.

2. A binder composition of Claim 1, wherein the boron compound is present in from about 2 to 10 parts by weight of boron compound per 100 parts of resole resin solids.

3. A binder composition of Claim 1, wherein the compo-sition pH is increased by the addition of sufficient ammonium hydroxide to raise the pH to about 7-10.

4. A binder composition of Claim 1, said resole resin comprising the reaction product of formaldehyde and a phenol, said phenol selected from the group of phenol, substituted phenols, substituted phenol mixture and mixtures thereof in a mol ratio 1.0 to 3.0, reacted in the presence of a basic catalyst.

5. A binder composition of Claim 2, wherein said sub-stituted phenol mixture has been prepared by alkylation of phenol with a mixture of carbocyclic compounds under acid conditions at a temperature in the range of 25 to 200°C., whereby 10 to 80 parts by weight of the mixture of carbocyclic compounds reacts with 100 parts by weight of phenol, said mixture of carbocyclic compounds comprising:
(A) from 10 to 40 parts by weight of compounds each molecule of which has:
(1) the indene nucleus, (2) from 9 to 13 carbon atoms, (3) as nuclear substituents from 0 to 4 methyl groups;
(B) from 5 to 70 parts by weight of com-pounds each molecule of which has:
(1) the dicyclopentadiene nucleus, (2) from 10 to 13 carbon atoms, (3) as nuclear substituents from 0 to 3 methyl groups;
(C) from 15 to 65 parts by weight of com-pounds each molecule of which has:
(1) a phenyl group substituted by a vinylidene group, (2) from 8 to 13 carbon atoms, (3) as substituents from 0 to 3 groups selected from the class consisting of methyl and ethyl; and (D) from 0 to 5 parts by weight of divinyl benzene.

6. A binder composition of Claim 2, wherein said phenol is phenol.

7. A binder composition of Claim 2, wherein said phenol is a substituted phenol having at least one radical selected from the group consisting of alkyl, aryl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, aralkyl, carbocyclic, halogen and mix-tures thereof.

8. A binder composition of Claim 2, wherein said basic catalyst is selected from the group consisting of ammonium hy-droxide, hexamethylene tetramine and triethylamine.

9. A binder composition of Claim 1, wherein said boron compound is boric acid.

10. A binder composition of Claim 1, wherein said boron compound is diammonium tetraborate or diammonium pentaborate and mixtures thereof.

11. A binder composition of Claim 1, wherein said resole resin comprises a solid content of from about 20 to 85 percent by weight, a water content of 2 to 35 percent by weight based on said resole resin, a viscosity of 5 to 5000 cps, said boron com-pound being present in from about 1 to 30 parts based on 100 parts of resole resin solids.

12. A laminate comprising a substrate, about 35 to 65 percent of resole resin solids, about 1 to 30 parts of boron compound accelerator based on 100 parts of said resole resin solids, the remainder up to 100 percent by weight being sub-strate, said boron compound being selected from the group con-sisting of boric acid, diammonium tetraborate, diammonium octa-borate, diammonium pentaborate and mixtures thereof.

13. A laminate of Claim 11, wherein said substrate is selected from the group of cellulosics, asbestos and glass as sheet substrates.